There is evidence that religious programs are effective in helping inmates commit to positive, rehabilitative values and resist the adoption of antisocial, crime-related values that pervade prison subculture. The authors argue that the effectiveness of religion in the prison environment should be measured by whether it changes inmate behavior in a positive direction. They offer 10 reasons that justify expanding religious services in prison. They include reduction in the likelihood of gang affiliation in prisons, a reduction in inmate misconduct, increased feelings of well-being among inmates, the integration of religious values into prison life, and increased motivation to participate in other prison rehabilitation programs. In the past 5 years, State and Federal legislation has strengthened religious freedoms for State inmates who can demonstrate a sincere attachment to the tenets of a specific religion. These rights include the right of Christians to wear crosses, the right to pursue religiously based dietary and fasting practices, and participation in sweat lodge purification rituals. Proponents of religious diversity in prisons have argued that expansion of the religious rights of all inmates, regardless of religious affiliation, serves the interests of both prison staff and prisoners. Christianity, however, continues to dominate prison religious life through aggressive and well-organized proselytizing and promotion of Christian values; for example, Prison Fellowship Ministries, the largest religious organization working in prisons, has developed partnerships with at least four States in conducting Christian-based programs for inmates. Most prison religious programs are conducted by prison chaplains and volunteers. 54 references